Conventional printed circuit ("PC") boards generally comprise a laminar construction of an electrically insulating substrate, a conductive layer and an adhesive. The adhesive bonds the conductive layer to the insulating substrate. For example, a copper cladding covers a surface of the insulating substrate which is commonly formed from one of the following materials: FR-4 epoxy, ceramic, glass-epoxy mixtures, polyimides, melamine and electrically insulating polymers. Various techniques are employed by printed circuit board manufacturers to etch away portions of the conductive layer leaving behind conductive traces which define desired electrical circuit geometries.
In addition, various technologies have been employed to attach and interconnect discrete surface-mounted, electronic components, including fuses, to these conductive traces to form circuit modules, assemblies or sub-assemblies. These discrete surfaced-mounted electronic components are typically soldered or electrically connected to the conductive traces. In many applications today, however, miniaturization requirements drive the design of PC boards, including single PC board applications where planar board "real estate" can be at a minimum and in multi-board applications where a plurality of PC boards must be vertically stacked. Accordingly, there is a need for a PC board assembly having thin film electrical fuses directly integrated into the circuit geometry or conductive traces to provide protection to the defined circuit geometries.
The present invention is designed to meet this need, and solve these and other problems.